Starter bar for continuous casting with electromagnetically secured mold stool

ABSTRACT

An improved starter bar for continuous casting which is provided with an electromagnet on one end thereof for detachably securing a mold stool to the starter bar.

United States Patent [151 3,684,002 Longhi [45] Aug. 15, 1972 [54] STARTER BAR FOR CONTINUOUS [5 6] References Cited CASTING WITH ELECTROMAGNETICALLY SECURED UN'TED STATES PATENTS MOLD STOOL 974,024 10/1910 Carter 164/49 1,480,191 l/1924 Wilson ..164/49 [72] 2,794,941 6/1957 Anderson ..335/291 x [73] Assignee: United States Steel Corporation 3,266,104 8/1966 Foldessy et al. 164/274 Filed: Feb. 1971 3,426,835 2/1969 Mlchelson ..l64/274 [21] Appl' No; 116,320 FOREIGN PATENTS OR APPUCATIONS Related US. Application Data 732,240 6/1932 France ..335/289 [63] Continuation-impart of Ser No. 814,764, April im y mi e -R Spencer Annear 9, 1969, abandoned. Attorney-Donald S. Ferito [52] US. Cl. ..l64/274, 164/82, 335/285, ABSTRACT I 335/289 An im d r prove starter bar for continuous casting Wl'llCl'l 511 Int. Cl. ..B22d 11/08 is d prov] e with an electromagnet on one end thereof [58] F'eld Search "164/ [333 for detachably securing a mold stool to the starter bar.

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2 Claim, 5 Drawing Figures STARTER BAR FOR CONTINUOUS CASTING WITH ELECTROMAGNETICALLY SECURED MOLD STOOL This application is a continuation-impart of my copending application Ser. No. 814,764, filed Apr. 9, 1969, now abandoned.

The present invention relates generally to a continuous casting apparatus and, more particularly, to an improved starter bar for continuous casting, which starter bar has a mold stool detachably connected therewith by electromagnetic means.

BACKGROUND OF THE INVENTION It is customary in the continuous casting of metals to provide apparatus including a vertical tubular mold open at the upper end for receiving molten metal and open at the lower end for the discharge of a metal casting. Cooling means made up of a plurality of water sprays are located below the mold for directing cooling water against the casting guide means. The casting guide means comprises a plurality of motor driven pinch rolls and idler guide rolls located between the water sprays for guiding the casting as it moves downwardly through the cooling zone. The cooling means is mounted on a suitable immovable frame. The guide rolls and pinch rolls are mounted for rotation in suitable mountings which are also mounted on an immovable frame.

It is necessary to close the lower discharge end of the mold initially when molten metal is being poured into the mold. This is usually done by the insertion of a starter bar into the bottom of the mold. The starter bar is an elongated metal bar, usually solid and rigid, which has a cross-sectional shape approximately the same as that of the mold with a slightly smaller cross-sectional area in order to permit ready insertion of the starter bar upwardly through the guide rolls and into the bottom of the mold. The starter bar, in addition to closing the discharge end of the mold while molten metal is being poured, also supports the metal column or casting as it descends through the guide rolls and pinch rolls.

In procedures prevalent prior to my invention, after the starter bar had passed through the pinch rolls, it was severed from the casting. One or more cutting torches located a short distance below the pinch rolls were usually employed for this purpose. These torches cut the casting a short distance above the top of the starter bar. The starter bar, with the short length of casting attached to the top thereof, was lowered vertically, supported by a suitable platform, basket, or the like. At the bottom of its vertical travel, the starter bar was lowered to a horizontal position and in this position was transported away. The short length of casting attached to the starter bar had to be removed before the starter bar could be used again. This increased production costs and decreased the efficiency of the continuous casting operation.

Prior to my invention, in attempts to overcome the above disadvantages, it became conventional practice to utilize some type of mechanical locking arrangement, such as, for example, interfitted mating lugs on the mold stool and the starter bar and a hinge pin passing through the interfitted lugs, to secure the mold stool to the starter bar. With this arrangement, it was necessary to remove the hinge pin to effect disconnection of the starter bar from the mold stool. Under certain conditions, as for example, in the event ofa short pour, while the mold stool was in the casting opening of the mold and casting was interrupted for any reason, the starter bar could not be disconnected from the mold stool in the usual way. Further, in the event that the starter bar was inadvertently prematurely disconnected from the mold stool prior to the time the casting entered between the pinch rolls, there was no contact between the casting and the pinch rolls to maintain continued downward movement of the casting. This, of course, resulted in an immediate stoppage of the continuous casting operation. Also, if a breakout occurred in the casting, i.e., where there was a breakout of the inner molten metal of the casting, the blister which formed became an obstacle to free passage of the casting through the pinch rolls so that resistance to downward movement of the casting occurred which caused the freezing pins of the mold stool to be pulled out of the casting. When this happened, it was impossible to reconnect the starter bar with the casting.

It is, accordingly, the primary object of my invention to provide an improved starter bar for continuous casting having a mold stool detachably connected thereto by electromagnetic means so that the mold stool and starter bar cannot be disconnected prematurely and can be easily reconnected after they have been intentionally disconnected during normal use.

It is a more specialized object of my invention to provide an improved starter bar for continuous casting as set forth in the statement of object above wherein an electromagnet is carried in one end of the starter bar for detachably securing a mold stool made of magnetic material to the starter bar.

As a corollary to the above abject, it is another object of my invention to provide an electric supply cable recessed in the starter bar with one end thereof connected with the electromagnet and its other and connected with a source of electric power.

Another object of my invention is to provide a starter bar as set forth by the statements of object above wherein air space in the form of an air compartment is interposed between the mold stool and the electromagnet whereby heat insulation is provided between the mold stool and the electromagnet.

These and other objects will become more apparent after referring to the following specification and attached drawing, in which:

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a partial diagrammatic elevational view of a continuous casting apparatus equipped with the improved starter bar of the invention;

FIG. 2 is a front elevational view of a preferred embodiment of the starter bar of the invention in position (with the pinch rolls omitted from one side for clarity) to support a mold stool in the bottom of a mold;

FIG. 3 is a sectional view taken substantially along the line III-III of FIG. 2;

FIG. 4 is a partial side elevational view of the mold stool and starter bar shown in FIG. 2 with the mold omitted; and

FIG. 5 is a view similar to FIG. 2 but showing a modified embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring more particularly to the drawing, and for the moment particularly to FIG. 1 thereof, reference numeral 2 designates a vertically disposed open-end continuous casting mold having a mold stool 4 inserted in and closing its casting end 6. The mold stool 4 is detachably connected with and supported by a starter bar 8. The starter bar is shown in operative position between pinch rolls and idler guide rolls 1 1 of a continuous casting apparatus preparatory to a casting operation.

As best shown in FIG. 2, starter bar 8 is provided with an elongated main body portion 12 having an electromagnet 14 in its upper end secured by screws 15. Mold stool 4, which is substantially scoop-shaped in form (as best shown in FIG. 4) and is provided with freezing pins 16 and locating pins 18 projecting therefrom, is made of magnetic material and is detachably connected with the starter bar by means of the electromagnet 14. The electromagnet 14 is provided with locating recesses 20 formed on its outer face for receiving the locating pins 18 of the mold stool so that the mold stool can be positioned and aligned properly relative to the starter bar.

The magnetic force exerted by the electromagnet 14, which isconventional in design, is preferably between 30 to 40 pounds per square inch which is adequate for maintaining the connection between the starter bar and the mold stool while the starter bar is supporting and drawing the mold stool 4 bearing the initial portion of the casting anchored to the freezing pins 16 therein downwardly through the pinch rolls 10 and idler rolls ll.

The electromagnet 14 is of all-welded construction which minimizes the possibility of moisture penetrating into the interior of the electromagnet as it passes through the water sprays of the cooling system. To further insure protection from moisture-caused malfunctioning, the magnet coils in the magnet shell may be completely wrapped in Glastic insulation (not shown) (Meade Magnet Company) which has a zero affinity for moisture. The dimensions of the electromagnet may be varied in accordance with type and size of product being continuously cast. Electromagnets suitable for use in accordance with my invention are manufactured by and obtainable from companies such as Meade Magnet Company, Ohio Magnet Company, Square D Electric Company and others.

In designing an electromagnet suitable for exerting the pulling force necessary for use in accordance with my invention, the following equation may be used to calculate the pulling force:

Force (8.94 X B X A)/10 Where B= 12,000 and A 6.5 square inches.

A cable 26 is connected at one end to a power source (not shown) remote from the starter bar and at its other end to the electromagnet 14 as at 24. An auxiliary cable 27 is provided disposed parallel with the cable 26 as a backup cable in the event that cable 26 malfunctions during a cast. Cable 27 is kept normally deenergized by means of a switch (not shown). Cables 26 and 27 are disposed in a recess 28 which extends along the length of the main body 12 of the starter bar 8. The purpose of the recess disposition of the cables 26 and 27 is to protect the cables when the starter bar passes through the pinch rolls and guide rolls during the casting operation. The opposite comers of the recess 28 are offset as at 30 for receiving a plurality of spaced retaining plates 32 which are secured by screws 34 which pass through the ends of the retaining plates into the offset portions of the recess 28. This arrangement disposes the retaining plates at least flush with or below the surface of the starter bar so that its movement through the pinch rolls and guide rolls is not interfered with.

It has been found that the pulling force of the electromagnet 14 will be reduced approximately 50 percent if the temperature in the area where the electromagnet is connected with the mold stool reaches 1,200 F. For this reason, if desired, the electromagnet 14 can be designed and manufactured to exert a pulling force approximately double the 30 to 40 pounds per squareinch which has been found to be necessary for successful operation of the starter bar of the invention. SInce the electromagnet 14 engages the bottom of the mold stool 4 outside of the mold 2 and is drawn downwardly immediately upon the initiation of casting, the water sprays of the continuous casting system that are used for cooling the casting as it descends keeps the electromagnet from becoming excessively heated. However, as stated above, if it is desired to insure the presence of the necessary pulling force, the electromagnet can be built with the greater force as explained above.

FIG. 5 illustrates a modified embodiment of the starter bar of the invention (elements comparable to elements of the preferred embodiment of the invention shown in FIGS. 1-4. aredesignated by the same reference characters but primed in FIG. 5). The modified embodiment of the starter bar of the invention is provided with an air compartment 36 on the bottom of the mold stool 4'. The air compartment is made up of a bottom plate 38, side plates 40, and spaced braces 42. The locating pins 18 are formed on the bottom of the bottom plate 38. With this arrangement when the starter bar is connected with the mold stool, the air space between the electromagnet 14 and the mold stool 4' which is provided by the air compartment 36 provides heat insulation to protect the electromagnet.

In operation, the mold stool 4 is placed in position in the bottom of the continuous casting mold 2. The starter bar 8 is moved upwardly through the pinch rolls 10 and guide rolls 11 into a position beneath the mold stool in which position the locating recesses 20 on the electromagnet l4 engage the locating pins 18 projecting from the mold stool. Thus, the electromagnet 14 is in contact with the bottom surface of the mold stool and the starter bar is properly positioned relative to and aligned with the mold. After casting starts and the cast slab is drawn downwardly between the pinch rolls 10, the electromagnet 14 is deenergized to brake the connection between and effect disconnection of the starter bar from the mold stool after the starter bar has completely cleared the pinch rolls. Although the foregoing description is directed to the preferred embodiment of the invention, it will be noted that the modified embodiment shown in FIG. 5 is operated in the same manner.

Although I have shown but two embodiments of my invention, other adaptations and modifications may be made without departing from the scope of the following claims.

I claim:

1. In a continuous casting apparatus including a mold having an open casting end, a mold stool of magnetic material adapted to fit into the close the casting end of the mold, and a starter bar for supporting-and controlling movement of the mold stool, the improvement therewith of an electromagnet disposed in the end of UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,684 O02 Dated August 15, 1972 Inventor(s) Anthony M. Longhi It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 37, "abject" should read object; line 40 after "other", "and" should read end Column 4, line 62, "brake" should read break Column 5, line 10, after "into", change "the" to read and Column 6, line 4, after "in" cancel "73".

Signed and sealed this 20th day of March 1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. 7 ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents FORM PO-1050 (10-69) USCOMM-DC 60376-P69 U.S GOVERNMENT PRINTING OFFICE I959 O-366-334.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,684 ,002 Dated August 15, 1972 Inventor(s) Anthony M. Longhi It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 37, "abject" should read object; line 40, after "other", "and" should read end Column 4, line 62, "brake" should read break Column 5, line 10, after "into" change "the" to read and Column 6, line 4, after "in" cancel "73".

Signed and sealed this 20th day of March 1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. 7 ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents FORM PO'WSO (10459) uscoMM-Dc 60376-P59 U.S GOVERNMENT PRINTING OFFICE: I959 0-366-33 

1. In a continuous casting apparatus including a mold having an open casting end, a mold stool of magnetic material adapted to fit into the close the casting end of the mold, and a starter bar for supporting and controlling movement of the mold stool, the improvement therewith of an electromagnet disposed in the end of said starter bar detachably securing the mold stool to the starter bar, said starter bar having a recess extending substantially lengthwise thereof, an electric power cable disposed in 73 said recess, one end of said cable being connected with said electromagnet and its other end being connected with an electric power source, and means for retaining said cable in said recess.
 2. Apparatus as defined by claim 1 including an air compartment interposed between said mold stool and said electromagnet whereby heat insulation is provided between said mold stool and said electromagnet. 